Inchemicotox

This page doesn’t really exist as such. If you go to Appearance > Menus, there is a top-level “About us” link, but that is just added there as a custom entity with the label “About us” and is a link to /about-us/collaborating-partners/.

If you want a real “About us” page, just edit this content right here, delete the custom link item in the Appearance > Menus options, then add the real “About us” page (this one!) and finally, move it up/down the list (and move it’s children underneath it) until you have what you want.